This invention is generally directed to toner and developer compositions, and more specifically the present invention is directed to toner compositions, including magnetic, single component, and colored toner compositions containing additives with certain morphologies. In one embodiment of the present invention, the toner compositions are comprised of resin particles, pigment particles, and metal salts of fatty acids, or metal salts with a sponge, or non-flake like morphology. There are also provided in accordance with the present invention positively, or negatively charged toner compositions comprised of resin particles, pigment particles, metal salts of fatty acids, or metal salts, such as zinc stearate, magnesium stearate, and the like, with a sponge like morphology, and optional charge enhancing additives. In addition, the present invention is directed to developer compositions comprised of the aforementioned toners, and carrier particles. Furthermore, in another embodiment of the present invention there are provided single component toner compositions comprised of resin particles, magnetic components, such as magnetites, and metal salts of fatty acids, or metal salts with a sponge, or non-flake like morphology. The toner, and developer compositions of the present invention are useful in electrophotographic imaging systems, especially those systems wherein blade cleaning of the photoconductive member is accomplished. Moreover, the toner and developer compositions of the present invention enable images with excellent resolution, and these compositions possess stable electrical properties for extended time periods. Furthermore, with the toner and developer compositions of the present invention there is enabled substantial uniformity of the toner triboelectric charge; improved toner flow characteristics, reduced undersirable toner impaction on, for example, the imaging member selected, and increased imaging member life. One important advantage associated with the compositions of the present invention reside in improvements in the overall developability of electrostatic latent images and in the uniformity thereof over extended time periods and imaging cycles exceeding, for example, 1,000,000 cycles in some instances in an electrophotographic imaging or printing system. While these characteristics are important in the production of black and white images, they are particularly important for faithful rendition of color images in which multiple primary color images are superimposed, where image densities are typically lower, and where variations in image density and hue are more noticeable than black. There is thus permitted with the compositions of the present invention a more stable development system requiring less complex control systems, and reduced maintenance of the imaging apparatus within which the compositions are incorporated.
Toner and developer compositions with metal salts or metal salts of fatty acids, including the stearates such as zinc stearate, are known reference for example U.S. Pat. Nos. 3,590,000; 3,655,374 and 3,983,045. These stearates, however, do not possess a sponge, or non-flake like morphology thereby enabling the advantages of the present invention. More specifically, the prior art stearates have platelet like morphologies which usually causes excessive accumulation of such stearates in a film on the receptor surface such that xerographic development characteristics may be severely affected in a detrimental manner. Furthermore, such film accumulation has a tendency to occur in an imagewise fashion since the stearate additives are electrostatically charged and tend to deposit preferentially according to the sign and magnitude of the development fields. This imagewise degradation in developability leads specifically to difficulties in maintaining developed image uniformity and to "ghosting". Ghosting refers to the objectionable imagewise modulation of image density within a given print or copy where that imagewise modulation follows image patterns generated on a prior print or copy cycle. The aforementioned disadvantages are alleviated, and/or minimized with the compositions of the present invention. Also, it is known that the aforementioned toner compositions with metal salts of fatty acids can be selected for electrostatic imaging methods wherein blade cleaning of the photoreceptor is accomplished, reference Palermiti et al. U.S. Pat. No. 3,635,704, issued Jan. 18, 1972, the disclosure of which is totally incorporated herein by reference.
Additionally, there are illustrated in U.S. Pat. No. 3,983,045 three component developer compositions comprising toner particles, a friction reducing material, and a finely divided nonsmearable abrasive material, reference column 4, beginning at line 31. Examples of friction reducing materials include saturated or unsaturated, substituted or unsubstituted, fatty acids preferably of from 8 to 35 carbon atoms, or metal salts of such fatty acids; fatty alcohols corresponding to said acids; mono and polyhydric alcohol esters of said acids and corresponding amides; polyethylene glycols and methoxy-polyethylene glycols; terephthalic acids; and the like, reference column 7, lines 13 to 43.
There were located as a result of a patentability search U.S. Pat. Nos. 3,501,294; 3,609,082; 3,740,334 and 3,983,045. These references disclose a myriad of stearates and like fatty acid salts in a wide range of particle sizes used as photoreceptor surface lubricants and the effect thereon in the electrophotographic process.
Illustrated in copending application U.S. Ser. No. 004,939/87, the disclosure of which is totally incorporated herein by reference, are toner and developer compositions with linear polymeric alcohols comprised of a fully saturated hydrocarbon backbone with at least about 80 percent of the polymeric chains terminated at one chain end with a hydroxyl group, which alcohol is represented by the following formula: EQU CH.sub.3 (CH.sub.2).sub.n CH.sub.2 OH
wherein n is a number of from about 30 to about 300, and preferably of from about 30 to about 100, which alcohols are available from Petrolite Corporation. Particularly preferred polymeric alcohols include those wherein n represents a number of from about 30 to about 50. Therefore, the polymeric alcohols selected have a number average molecular weight as determined by gas chromatography of from about greater than 450 to about 1,400, and preferably of from about 475 to about 750. In addition, the aforementioned polymeric alcohols are present in the toner and developer compositions in various effective amounts as finely divided uniformly dispersed external additives. More specifically, the polymeric alcohols are present in an amount of from about 0.05 percent to about 20 percent by weight. Therefore, for example, as external additives the polymeric alcohols are present in an amount of from about 0.05 percent by weight to slightly less than about 5 percent by weight.
The aforementioned copending application also discloses the addition of charge control additives to the toner composition.
Other references of interest which disclose the use of amides as toner additives include U.S. Pat. Nos. 4,072,521; 4,073,649 and 4,076,641. Furthermore, references of background interest are U.S. Pat. Nos. 3,165,420; 3,236,776; 4,145,300; 4,271,249; 4,556,624; 4,557,991 and 4,604,338.
Moreover, toner and developer compositions containing charge enhancing additives, especially additives which impart a positive charge to the toner resin, are well known. Thus, for example, there is described in U.S. Pat. No. 3,893,935 the use of certain quaternary ammonium salts as charge control agents for electrostatic toner compositions. There is also described in U.S. Pat. No. 2,986,521 reversal developer compositions comprised of toner resin particles coated with finely divided colloidal silica. According to the disclosure of this patent, the development of images on negatively charged surfaces is accomplished by applying a developer composition having a positively charged triboelectric relationship with respect to the colloidal silica. Further, there is illustrated in U.S. Pat. No. 4,338,390, the disclosure of which is totally incorporated herein by reference, developer and toner compositions having incorporated therein as charge enhancing additives organic sulfate and sulfonate compositions; and in U.S. Pat. No. 4,298,672, the disclosure of which is totally incorporated herein by reference, positively charged toner compositions containing resin particles and pigment particles, and as a charge enhancing additive alkyl pyridinium compounds, inclusive of cetyl pyridinium chloride.
Other prior art disclosing positively charged toner compositions with charge enhancing additives include U.S. Pat. Nos. 3,944,493; 4,007,293; 4,079,014; and 4,394,430.
Although the above described toner and developer compositions are useful for their intended purposes, there is a need for improved compositions. More specifically, there is a need for toner compositions, including single component compositions which possess many of the advantages indicated herein. There is also a need for toner compositions with additives such as metal salts, or metal salts of fatty acids, as well as mixtures thereof with a sponge, or non-flake like morphology. These compositions are particularly useful in electrostatic imaging processes wherein blade cleaning is utilized for the removal of unwanted toner particles from the photoreceptor surface. In addition, there is a need for toner and developer compositions that maintain their triboelectrical characteristics for extended time periods exceeding, for example, 100,000 developed images. In addition, there is a need for toner and developer compositions, including color compositions that simultaneously maintain stable electrical characteristics for extended time periods, and maintain the toner triboelectric charge at a uniform value. Furthermore, there is a need for single component toners, and colored toners that possess many of the aforementioned characteristics. Also, there is a need for toner and developer compositions containing metal stearate charge control agents which do not cause either imagewise variations in developability or lack of development to high image output densities through excessive accumulation of such agents on the photoreceptor surface. Also, there is a need for toner and developer compositions containing lubricating agents with certain morphologies which provide appropriate lubrication of the receptor surface enabling use of blade cleaners but which do not lead to either imagewise variations in developability or lack of development to high image output densities through excessive accumulation of such lubricating agents on the surface of the photoreceptor.